Raman spectroscopy is an analytical technique which uses light scattering to identify and quantify molecules. When light of a single wavelength (monochromatic) interacts with a molecule, the light scattered by the molecule contains small amounts of light with wavelengths different from the incident light. The wavelengths present in the scattered light are characteristic of the structure of the molecule, and the intensity of this light is dependent on the concentration of these molecules. Thus, the identities and concentrations of various molecules in a substance can be determined by illuminating the substance with monochromatic light and then measuring the individual wavelengths and their intensities in the scattered light.
A continuing problem with Raman spectroscopy is the very low intensity of the scattered light compared to the incident light. Elaborate spectrographs, having high light gathering power and dispersion, high stray light rejection, and sensitive detectors, are required to isolate and measure the low intensity Raman scattered light. These instruments are costly and delicate, and are not well suited for use in industrial manufacturing or processing facilities. As a result, they have rarely been used outside of laboratory environments. Improvements in the fields of lasers, optical fibers, and filters enable one to remotely locate a fiberoptic probe from its laser light source and from its spectrograph.
It will be appreciated that there is a need in the art for a spectrograph apparatus which is compact and robust, suitable for use in industrial applications, which provides quick and accurate results.